Wow. Thank you. These formulas are quite complex.

Your assumption is entirely right. Sometimes one would start with cycle 1, sometimes with cycle 2. Where would you insert the dropdown (for the dropdown I'd choose Cycle 1/Cycle 2.

Cycle D and F do not work for me. But this could be due to the fact that I can try this with Excel 2003 only. Can try it with a newer version later. Or do you think there could be an error which prevents this from working?

Cell E2 is already filled... even when D2 is empty. Is this correct?